The present invention is concerned with riveting tools for use in setting blind rivets of the type which comprise a tubular rivet having a head, and a mandrel which passes through the tubular rivet and comprises a setting head which engages an end face of the tubular rivet remote from its head and a pulling head which is pulled to move the mandrel relative to the rivet to set it. Such rivets are commonly referred to as "double headed rivets".
A tool for setting a double headed rivet requires a nose piece supporting a pulling assembly, adapted to grip the pulling head of the mandrel to pull the rivet to set the rivet, and an abutment assembly arranged to engage the head of the rivet during its setting. It is necessary that the abutment assembly is capable of moving into an open position to allow the passage of the pulling head of the mandrel past the abutment assembly to engage the pulling assembly and then into a closed position to provide an abutment to engage the head of the rivet.
In a known riveting tool for use with double headed rivet, described in U.S. Pat. No. 4,628,722 the abutment assembly comprises a plurality of abutment members extending generally axially of the nosepiece around the pulling assembly and movable between an open position, in which the pulling head of the mandrel may be passed through the abutment assembly to be engaged by the pulling assembly and a closed position in which the abutment members provide an abutment to engage the rivet head. The abutment members are moved radially between their open and closed positions by a sleeve which is moved axially of the tool by a pneumatic piston and cylinder arrangement. This piston and cylinder arrangement is actuated by a sensor which detects when a rivet has been positioned in the pulling assembly and then causes the abutment members to close. This construction is somewhat complex and expensive particularly in that two separate drive pistons are required.
Another riveting tool for use with double headed rivets, described in U.S. Pat. No. 5,337,463, includes a pulling assembly arranged to grip the pulling head of a mandrel to set the rivet and an abutment assembly extending generally axially around the pulling assembly and movable between an open position, in which the pulling head of the mandrel may be passed through the abutment assembly to be engaged by the pulling assembly, and a closed position in which the abutment members provide an abutment to engage the rivet head. The abutment members are mounted for axial movement against spring pressure and comprise cam means which on such axial movement cause the abutment members to move from their open to their closed positions. The pulling assembly comprises a collet assembly comprising collet members having latches adapted to engage behind the head of a mandrel. When a blind rivet is presented axially to the tool, the head of the rivet engages the abutment members and, when the rivet is pushed into the tool so that the pulling head of the mandrel is engaged by the latches of the collet members, the abutment members are moved axially relative to the nosepiece to move from their open to their closed position, and close firmly about the mandrel. This design is primarily suited for use with rivets fed by hand or from an external rivet presentation device.
It is an object of the present invention to provide a riveting tool for use with double headed rivets which is simpler and more economical in construction.
It is another object of this invention to provide a riveting tool for use with double headed rivets which is adapted for use with an automatic rivet loading system.